In recent years, the interior trim of automobiles tends to be luxury, and to cope with the demand for the protection of the interior trim from deterioration and to reduce the load of air conditioning, a green-tinted glass having ultraviolet and infrared radiation absorbing power imparted thereto has been proposed as window glass of automobiles.
For example, glass having an ultraviolet transmission reduced to about 38% or less, a total solar energy transmission limited to about 46% or less and a visible light transmission of at least 70% for ensuring the vision from the inside of an automobile, is known. Further, there is a recent trend that a bluish green tint is preferred for such a green-tinted glass for automobiles.
It is known that the total solar energy transmission can be decreased by increasing the absolute amount of ferrous oxide (FeO) out of the iron oxides introduced into the glass, and almost all of conventional infrared radiation absorbing glasses use this method.
On the other hand, various methods have hitherto been proposed on a method for decreasing an ultraviolet transmission. For example, JP-A-6-56466 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses an ultraviolet radiation absorbing glass having a green tint, which comprises a soda-lime-silica basic glass composition having incorporated therein, as coloring components, 0.53 to 0.70% of total iron oxides in terms of Fe.sub.2 O.sub.3, 0.5 to 0.8% of CeO.sub.2, 0.2 to 0.4% of TiO.sub.2, and 30 to 40% of FeO in terms of Fe.sub.2 O.sub.3 based on the total iron oxides in terms of Fe.sub.2 O.sub.3.
JP-B-6-8812 (the term "JP-B" as used herein means an "examined Japanese patent publication") discloses an ultraviolet radiation absorbing glass having a green tint, which comprises, in % by weight, a basic glass composition comprising 65 to 75% of SiO.sub.2, 0 to 3% of Al.sub.2 O.sub.3, 1 to 5% of MgO, 5 to 15% of CaO, 10 to 15% of Na.sub.2 O, and 0 to 4% of K.sub.2 O, and coloring components comprising 0.65 to 1.25% of total iron oxides in terms of Fe.sub.2 O.sub.3, 0.2 to 1.4% or 0.1 to 1.36% of CeO.sub.2 and 0.02 to 0.85% of TiO.sub.2.
JP-A-8-208266 discloses an ultraviolet and infrared radiation absorbing glass having a green tint, which comprises a soda-lime glass having incorporated therein 0.52 to 0.63% of total ion oxides in terms of Fe.sub.2 O.sub.3, 0.9 to 2% of CeO.sub.2, 0.2 to 0.6% of TiO.sub.2 and 0 to 0.002% of CoO, as coloring components.
Since cerium oxide is expensive, an ultraviolet and infrared radiation absorbing glass having decreased cerium oxide content has also been proposed.
For example, JP-A-4-231347 describes a green-tinted ultraviolet radiation absorbing glass, which comprises a soda-lime-silica basic glass composition having incorporated therein, as coloring components, more than 0.85% by weight of total iron oxide (T-Fe.sub.2 O.sub.3) in terms of Fe.sub.2 O.sub.3, with the FeO/T-Fe.sub.2 O.sub.3 ratio being less than 0.275, and less then 0.5% by weight of CeO.sub.2.
JP-A-6-191881 discloses an ultraviolet radiation absorbing glass having a pale green tint, which comprises a soda-lime-silica basic glass composition having incorporated therein a coloring agent part comprising less than 2.0% of TiO.sub.2 and more than 0.6% of total iron oxide (T-Fe.sub.2 O.sub.3) in terms of Fe.sub.2 O.sub.3 with the FeO/T-Fe.sub.2 O.sub.3 ratio being less than 0.35.
JP-B-7-121815 discloses an ultraviolet radiation absorbing green glass, which comprises a soda-lime glass having incorporated therein 0.7 to 0.95% of total iron oxide in terms of Fe.sub.2 O.sub.3 and 0.19 to 0.24% of FeO. In this case, it is very important that the SO.sub.3 content is within an extremely narrow range of from 0.20 to 0.25% by weight.
In the above-described conventional ultraviolet and infrared radiation absorbing glasses, the ultraviolet absorbing power is imparted by the ultraviolet absorption of Fe.sub.2 O.sub.3, CeO.sub.2 and TiO.sub.2 individually or by the interaction thereof. Of these components, the ultraviolet absorption of Fe.sub.2 O.sub.3 or the ultraviolet absorption by the interaction between TiO.sub.2 and FeO extends to the visible region. Accordingly, when the glass is designed to have an increased ultraviolet absorption, the visible light transmission in the short wavelength region is simultaneously lowered and as a result, the glass comes to have a yellowish tint. Therefore, in order to enhance the ultraviolet absorbing power without giving a yellowish tint which is not preferred as a glass for automobiles, the composition must have a large CeO.sub.2 content.
However, Fe.sub.2 O.sub.3 and CeO.sub.2 are an oxidizing agent and when these are contained in a large amount, it is very difficult to obtain a glass which has an oxidation-reduction equilibrium of iron oxide shifted to the reduction side and thus contains a large amount of FeO to thereby exhibit excellent infrared absorption. More specifically, in order to cancel the oxidation action of Fe.sub.2 O.sub.3 and CeO.sub.2 and shift the oxidation-reduction equilibrium of the iron oxide to the reduction side more than usual, a reducing agent must be added to a batch in a larger amount than usual. This encourages decomposition of the salt cake (sodium sulfate) which accelerates melting of the batch, particularly, melting of the quartz sand, as a result, not only the solubility of batch, particularly, of quartz sand is worsened to cause extreme reduction in the melting capacity but also floating of undissolved quartz sand (so-called scum) may be generated or a ream defect having a larger silica content (so-called silica-rich ream) may come out on the surface.